The present invention is generally related to the field of printing and, more particularly, is related to a system and method for fusing toner in a laser printing device.
In conventional laser printers, the fusing of toner onto paper is generally accomplished by applying heat to the toner and the paper with an external heat source. This external heat source usually includes one or more rollers that are heated to the fusing temperature. The rollers may be heated, for example, by placing long, thin, high-wattage incandescent lamps inside the rollers to which a proper power source is applied. The radiant energy from the incandescent lamps heats the rollers from the inside to the fusing temperature. Toner is fused to paper by running the paper between the heated rollers accordingly. Another approach employed to fuse toner to paper is to apply a high-intensity flash lamp to the toner/paper to perform so called xe2x80x9cflash fusingxe2x80x9d.
There are disadvantages to the conventional toner fusing approaches outlined above. For example, conventional fusing apparatus require complicated heat management strategies that result in sophisticated mechanical, thermal and electrical design that is relatively expensive. Such fusers are large, heavy, slow to reach operating temperature, and are inefficient users of energy. The heat that is generated by such fusers is generally transferred to many areas inside a printer where heat is undesirable. Consequently, materials selected for use in the design of laser printers using conventional fusers is highly constrained by heat considerations. The actual fusing temperature achieved by conventional fusers varies widely due to inherent difficulty of sensing and rapidly adjusting fuser temperature with available control systems. Improper fusing temperature and the spatial and temporal variation of fusing temperature cause a variety of print quality defects. Conventional fusers are also responsible for a large fraction of the media damage, jams, and damaged printers experienced by printer users.
In light of the foregoing, the present invention provides for an apparatus and method for fusing toner to a print medium. In one embodiment, the apparatus includes a laser source optically coupled to a predefined position in a print medium pathway. A laser beam generated by the laser source is directed to fall upon the print medium shuttled along the print medium pathway. Finally, a laser controller is coupled to the laser source to control the laser beam to generate a predefined fusing exposure of the print medium by the laser beam.
In addition, the present invention also encompasses a method for fusing toner to a print medium. The present method comprises the steps of: generating a laser beam, coupling the laser beam to a predefined position in a print medium pathway, wherein the laser beam is directed to fall upon the print medium shuttled along the print medium pathway, and, controlling the laser beam to generate a predefined fusing exposure at the predefined position to fuse an amount of toner to the print medium.
A number of advantages are realized by fusing toner to a print medium according to the present invention. Specifically, the complicated heat management strategies associated with conventional fusing systems are not required in the present invention as there are no heated rollers for toner fusing. The fusing apparatus according to the present invention can be relatively small, lightweight and efficient as compared with the conventional fusing systems and requires no fuser warm up time before use. Because heat generation is minimized in the present invention, materials selected for use in the design of laser printers can be less constrained by heat considerations. Also, control of fusing temperatures is not as great a concern and a large fraction of print media damage and jams may be alleviated. In addition, the present invention provides for the selective fusing of print media, where areas without toner to fuse are not subjected to fusing energy as in conventional fusers. In addition, print media of greatly varying thicknesses may be fed through a laser printer or other device that employs a toner fusing apparatus according to the present invention. Specifically, it is not necessary to heat the full thickness of the print media itself for proper fusing according to the present invention, thereby allowing the use of print media with greater thickness as compared with print media used in conventional fusing systems.
Other features and advantages of the present invention will become apparent to a person with ordinary skill in the art in view of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention.